'What is that disgusting blob?' — Mystery creature found in Lake Paro identified

Large numbers of a bizarre aquatic organism resembling salamander egg sacs have been found in the upper reaches of the North Han River in Gangwon Province. The creature is Pectinatella magnifica, an invasive freshwater bryozoan that sparked debate over its ecological impact in the past. Local fishermen say fish catches decline as the colonies multiply.

On Saturday, bryozoan colonies were spotted throughout Heart Island, a tourist attraction on Lake Paro in Dosong-ri, Gandong-myeon, Hwacheon-gun. The colonies were distributed in clumps in shallow water.

Particularly large numbers were found along an embankment connecting the mainland to the island, where blocked water flow makes stagnation common. Fishermen said the colonies grow more numerous during droughts and hot weather.

Yoo, a 67-year-old inland fisherman, told Yonhap, "When it's unusually dry or hot, more of those disgusting things come out. When that happens, the catch drops and it becomes a real headache."

Pectinatella magnifica is an invasive species in which microscopic individuals, each about 1 millimeter in size, cluster on a gelatinous secretion to form large, rugby ball-shaped colonies. About 99.5 percent of the organism's body is water, with the remainder composed of gelatin and organic matter.

The species spread across South Korea in 2014, reigniting debate over its ecological effects. At the time, the Ministry of Environment announced, based on research by the National Institute of Environmental Research and other specialist institutions, that the bryozoan posed no ecotoxic or harmful effects on ecosystems.

However, environmental groups argue that the creature's appearance is evidence of abundant algae and aquatic microorganisms — its food sources — and therefore signals deteriorating water quality. A mass occurrence of the bryozoan in the Lake Paro area of Hwacheon-gun had not previously been recorded.